It is known that flexible shafts or cables can be provided for driving tools from a source of rotary power or the like. Among the tools which can be thusly driven are vibrator heads such as disclosed in U.S. Pat. No. 5,108,189. Such cables consist of inner cores surrounded by flexible shaft shields or housings. The ends of such cores are adapted for engagement by a prime mover such as a rotary electric motor at one end thereof while the other end is adapted for engagement with a tool which can be driven by a rotary force.
In one known type of arrangement, the inner core is provided with square ends which slide into square holes one of which is provided at the end of a rotary motor shaft while the other end is also squared to be accommodated in a square hole associated with the tool which is to be driven. The ends of the core shield or housing are threaded and can be threadably engaged with threaded openings respectively provided in the rotary motor shaft and in the tool.
By way of attempts to simplify the removal of a flexible cable from the associated motor, various quick change couplings have been employed. To accommodate the core of a flexible cable, it is also known to employ ball bearings to fix the position of the driven cable and particularly the core thereof. Such an arrangement is expensive to make and the ball bearings develop heat and wear out comparatively rapidly thereby requiring replacement.
In another arrangement, the core of a flexible cable slips directly into a square hole in a rotary shaft associated with an electric motor. In this arrangement as well as in other arrangements, the core is covered with grease which readily exudes out of the flexible core housing upon detachment of the cable from the tool and/or driving motor.
In still another arrangement, an adaptor is provided for the core of a flexible cable, the core being provided with a collar by means of which the adaptor forces the core into engagement with a square driving hole. The adaptor is engaged by a spring-loaded plunger by means of which the core is retained in the square driving hole associated with the associated rotary electric motor. The problem here is that the collar rotates at a high speed and rubs against a shoulder in the adaptor by means of which the core is forced into a hole engaging position. This arrangement undersirably develops heat and furthermore is subject to frictional wear due to which the coupling eventually becomes unusable.
In researching my invention in order to evaluate further the novelty thereof, the following U.S. patents were found: U.S. Pat. Nos. 867,162; 2,715,822; 2,820,655; 2,885,232; 3,002,365; 4,392,836 and 5,149,302.
In U.S. Pat. No. 5,149,302, H. Yano discloses a device for connecting a screw shaft and a drive cable of a shoulder-belt position adjusting device useful in connection with a seat belt. In the disclosed device, a projection extends through a stopper and is adapted for insertion into a hole of a rotatable member. When two joints are moved together, a projection is brought into engagement with the end surface of a receiving element. As a consequence, one of the joints is prevented from being disengaged from the second of the joints. This provides a connection between the screw shaft and the drive cable. A projection is inserted into a bore so as to transmit rotation of the coupling member to the rotatable member. This arrangement is such as to maintain surfaces together which generates heat and provides for relatively rapid wear. The arrangement also lacks the positive engagement of elements to provide a force which holds the coupled elements together.
N. Sugawara discloses in U.S. Pat. No. 4,392,836 a device for connecting a speedometer to a flexible shaft. In this arrangement the tips of two claws engage an annular groove thereby connecting a driving device to the speedometer. With a front tube part fitted onto a stem, an end part of the inner shaft associated therewith is fit into a hole of square cross-section provided in a rotating shaft. Under this condition, the shafts rotate together with the inner shaft. In disconnecting the speedometer from the flexible shaft, the disconnecting work is described as being easily performed by the pushing of an arm member against a connecting tube described in the patent. This structure lacks many features of the present invention as will be seen hereinbelow.
In U.S. Pat. No. 3,002,365, J. Liljequist reveals a coupling device which provides, so it is alleged, for a quick change marine propeller. The forward end of a mounting sleeve is radially grooved to engage a shear pin for transmitting motion from the propeller shaft to the propeller through a mounting sleeve 15. Employed in this transmission is an elastomeric annular cushion and a hub. A key is provided which, when in its normal position of displacement subject to a bias spring, brings the associated plunger into a position substantially flush with the external surface of the hub. In this condition, the key engages a shoulder of a propeller to maintain the propeller securely in place on the shaft with its driving sleeve operatively engaged with the shear pin. This arrangement similarly fails to display the various features of the invention as will be shown hereinafter.
In U.S. Pat. No. 2,715,822, P. Anderson discloses the use of a resilient O-ring. The ring is rolled into a rotor shaft bore wherein it is deformed and placed under radial compression in order to possess a gripping capacity relative to a drive shaft and a rotary shaft. This couples the shafts together so that drive can be transmitted from one to the other. This arrangement also fails to embody various features of the present invention as will be shown hereinafter.